Materials which are suitable for use in making implantable or insertable medical devices typically exhibit one or more of the qualities of exceptional biocompatibility, extrudability, moldability, fiber forming properties, tensile strength, elasticity, durability, and the like. Moreover, in medical devices from which a therapeutic agent is released, suitable materials for use will typically exhibit a release profile appropriate for the disease or condition being treated.
In this regard, controlled release of therapeutic agents by means of polymeric materials has existed in various forms for many years. For example, numerous polymer-based medical devices have been developed for the delivery of therapeutic agents to the body. Examples include drug eluting coronary stents, which are commercially available from Boston Scientific Corp. (TAXUS), Johnson & Johnson (CYPHER), and others.
Consequently, there is a continuing need for high performance polymeric materials that can be used in medical devices, including those which regulate the release therapeutic agents. Among various attributes of the polymer or polymers making up such materials, the molecular weight, architecture (e.g., linear, cyclic, branched), monomeric constituents, as well as the proportion and distribution of the monomeric constituents (where copolymers are involved) will commonly influence one or more characteristics of the materials, including the biocompatibility, mechanical characteristics, processability, and therapeutic agent release profile (where a therapeutic agent is present and is released).